implements the writing of ibrav in qeschema

* reads bravais_index and use_alternative attributes from the
atomic_structure element and uses them to select an ibrav

* uses the cell vectors to compute A,B,C COSAB, COSBC and COSCA parameters

status

qeschema/cards.py

@@ -234,6 +234,8 @@ def get_cell_parameters_card(name, **kwargs):
         logger.error("Missing required arguments when building CELL_PARAMETERS card!")
         return []
     # Add cell parameters card
+    if atomic_structure.get('@bravais_index'):
+      return []
     cells = atomic_structure.get('cell', {})
     if cells:
         lines = ['%s bohr' % name]

qeschema/converters.py

@@ -325,7 +325,7 @@ class PwInputConverter(RawInputConverter):
         'atomic_structure': {
             '@nat': 'SYSTEM[nat]',
             '$': [
-                ('SYSTEM[ibrav]', options.set_ibrav_to_zero, None),
+                ('SYSTEM[ibrav]', options.get_ibrav, None),
                 ("ATOMIC_POSITIONS", cards.get_atomic_positions_cell_card, None),
                 ("CELL_PARAMETERS", cards.get_cell_parameters_card,  None)
             ],